I think the number one question I get from clients when booking their family sessions is: "What should we wear?" -- I promise, it is NOT rocket science! My best advice to you is this: try to COORDINATE, not MATCH! Have you ever seen photos on a friends wall where they are all wearing jeans and white t shirts? I bet that photo was taken in the 90s! I promise although you think its a great idea, its NOT! I encourage my clients to wear colour, and prints. Its okay to mix and match prints, it makes things interesting. A great photo has depth, and you can help provide that by layering your pieces and wearing great accessories.
Think of dressing your family, like decorating a room in your home. You have your main colours, and your pillows and curtains and other accessories provide your pops of colour. It's easy to do that with your family outfits! You can definitely all wear jeans, and keep a neutral shirt like grey or white, but then add in colour with scarves, sweaters, belts, etc. My FAVOURITE place to shop for coordinating outfits is Old Navy. I swear they do the work for you! You can go to any place in the store and find things for the whole family that go together. I have gone online and found you all some great options at Old Navy and the Gap.
Remember, you don't have to go shopping to clothes, I am sure you can find things in your closet you already own! When I dress my family for photos, I normally pick my favourite outfit and build the rest of the family around me (Mom is most important right?!) If you need inspiration, Pinterest is a great resource! Just type in "family photo outfit inspiration" and tons of ideas will come up. You can also search for colour schemes for your house, and use that as inspiration for your outfits. I have started a Pinterest Board dedicated to this, and you can check it out here! https://www.pinterest.ca/1000wordslac/family-photo-outfit-inspiration/